From the prior art, safety brakes for elevators are known which consist essentially of a brake housing with a brake wedge. As a rule, the safety brakes are arranged in a pair arrangement on an elevator car or a counterweight of the elevator. The elevator car and the counterweight are guided along guiderails. In case of need, the safety brake can act on the guiderails in order to stop the elevator car and/or the counterweight. The safety brakes are controlled by speed governors or safety controls. This safety control, or the speed control, monitors an operation of the elevator and, in case of need, actuates the safety brake when, for example, an excessively high travel speed is detected. As a rule, this actuation should take place rapidly. Various efforts have been undertaken to improve the engagement times of such safety brake. In addition, in the prior art, there are approaches to fitting such devices with an automatic resetting system.
EP 1 902 993 A1, for example, shows a safety brake which, instead of a wedge, has a friction roller. The friction roller moves in a motion link, which is held by an electromagnet. When the device is triggered, the electromagnet is de-energized. The latter releases the motion link, which, via a spring, together with the friction roller, is pressed against a guiderail of an elevator. Between the motion link and the magnet, a gap occurs. Through displacement of the friction roller into an engaged position, the motion link is again pressed in the direction of the magnet, whereby the magnet can be re-energized and holds the motion link in the rest position again. Upon release of the safety brake, the friction roller is pulled by a spring mechanism into its original position. The spring that presses on the motion link, and the spring that pulls the friction roller back, act in opposite directions. This is particularly disadvantageous, since neither of the two springs can fully develop its force.
A further disadvantage is that it takes relatively long until the safety brake is in an engaged position and can brake the elevator.